Thorium enolate

The formation constants of an actinium isopropyltropolonate complex were determined. Thermochemically relevant studies of thorium enolates generally involve bis(pentamethyl-cyclopentadienyl)thorium derivatives. Cp 2Th(Cl)(C(0)CFl2Bu-f) with an anionic acyl group that readily rearranges to the isomeric enolate Cp 2Th(Cl)OCH=CHBu-t. The Z-isomer is formed upon heating and the -isomer upon catalysis with Cp 2ThH2. Is the E or Z enolate thermodynamically more stable For the simple alkyl enolates MeCH=CHOR, the equilibration reaction of the Z- and E-isomers is nearly thermo-neutral . Consider the two species Cp 2Th(H)OCH(Bu-t)2 and Cp 2Th(H)0-2,6-C6H3 (Bu-f)2. The reversible addition of CO yields the rp- formyl derivative in reactions that are 19 4 and 25 6 kJmoR exothermic. These formyl species dimerize to form the classical enediolate, Cp 2Th(OR)OCH=CHO(OR)ThCp 2. This product is formed as the Z-isomer, plausibly thermodynamically preferred over the -isomer, much as (Z)-MeOCH=CHOMe is preferred over its E-counterpart by 6.0 0.2 kJmoR. ... 

If hydrogen gas is added to the reaction mixture of J, and 11 the hydrogenolysis reaction of thorium-to-carbon sigma bonds (J-1 22) allows interception of species 13 and thus, catalytic hydrogenation of the inserted carbon monoxide functionality. At 35 C under 0.75 atm initial H2 pressure with [JJ =9.0 x 10" M and [ 1JJ = 6.5 x 10" M, hydrogenation and isomerization are competitive and both the enolate and the alkoxide reduction product 14 are produced (eq.(13)). Under these conditions, turnover fre-... 

Phosphine Chalcogenides as Ligands. - The complexation of lanthanide and actinide ions by phosphine oxide ligands remains an active area, and a theoretical assessment of the coordination of phosphine oxides (and phosphate esters) by trivalent lanthanide ions has appeared." Trivalent lanthanide complexes of the functionalised enol phosphine oxide (265), (and a related phosphonate), have been describedComplexes of thorium(iv) with bis(di-phenylphosphino) ethane dioxide and bis(diphenylphosphinoyl)amide have also been characterised." Calixarene systems which bear phosphine oxide... 

A series of phosphido complexes has been examined. The structure of Cp 2Th(PPh2)2 shows no evidence for significant Th-P multiple bonding.When the lutetium complexes (39) was structurally characterised it was shown to contain a puckered 4-membered ring. The complex (40) has been proposed to contain a platinum-thorium bond. Carbon-hydrogen bond activation including cyclometallation reactions have been reported for Cp 2ThR2 complexes.The first enolate complexes of the type [Cp 2Y(u-OCH=CH2)]2 have been described... 

---